{"title":"Accessing Homoleptic Neutral and Anionic Five-coordinate Pr(IV) Siloxide Complexes","authors":"Pragati Pandey, Megan Keener, Thayalan Rajeshkumar, Rosario Scopelliti, Andrzej Sienkiewicz, Ivica Zivkovic, Laurent Maron, Marinella Mazzanti","doi":"10.1039/d5sc05500h","DOIUrl":null,"url":null,"abstract":"Structurally characterized Pr(IV) complexes are limited to four examples because the ligands and reaction conditions capable of stabilizing Pr(IV) remain elusive. Here we identify reaction conditions allowing the synthesis of Pr(IV) compelxes that were originally thought difficult to isolate. The Pr(IV) complexes of the tris(tert-butoxy)siloxide (–OSi(OtBu)3) and triphenylsiloxide (–OSiPh3) ligands, [PrIV(OSi(OtBu)3)4] (2-PrOtBu), [MPrIV(OSiPh3)5] (5M-PrPh) (M = K, Cs), and [KDB18C6][PrIV(OSiPh3)5], (5[KDB18C6-PrPh]) were isolated and fully characterized upon the oxidation of the tetrakis and pentakis(siloxide)praseodymium(III) ate complexes, [KPrIII(OSi(OtBu)3)4] (1-PrOtBu) and [M2PrIII(OSiPh3)5] (4M-PrPh) (M = K, Cs), using the thianthrene radical cation tetrafluoroborate oxidant, thiaBF4. The crucial role of reagents and reaction conditions, like thiaBF4 over the magic blue oxidant and non-coordinating over coordinating solvents, are demonstrated for the isolation of high valent Pr(IV) complexes. The solid state structural and electrochemical properties were studied and further augmented with theoretical calculations. The Pr(IV) oxidation state was further confirmed by electron paramagnetic resonance (EPR) and SQUID magnetometry measurements. Complexes 5M-PrPh and 5[KDB18C6]-PrPh provide the first example of anionic Ln(IV) complexes demonstrating the possibility of accessing charged Pr(IV) complexes as a tool to manipulate the redox potential and therefore access to more stable complexes with the same ligand.","PeriodicalId":9909,"journal":{"name":"Chemical Science","volume":"40 1","pages":""},"PeriodicalIF":7.4000,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Chemical Science","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1039/d5sc05500h","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Structurally characterized Pr(IV) complexes are limited to four examples because the ligands and reaction conditions capable of stabilizing Pr(IV) remain elusive. Here we identify reaction conditions allowing the synthesis of Pr(IV) compelxes that were originally thought difficult to isolate. The Pr(IV) complexes of the tris(tert-butoxy)siloxide (–OSi(OtBu)3) and triphenylsiloxide (–OSiPh3) ligands, [PrIV(OSi(OtBu)3)4] (2-PrOtBu), [MPrIV(OSiPh3)5] (5M-PrPh) (M = K, Cs), and [KDB18C6][PrIV(OSiPh3)5], (5[KDB18C6-PrPh]) were isolated and fully characterized upon the oxidation of the tetrakis and pentakis(siloxide)praseodymium(III) ate complexes, [KPrIII(OSi(OtBu)3)4] (1-PrOtBu) and [M2PrIII(OSiPh3)5] (4M-PrPh) (M = K, Cs), using the thianthrene radical cation tetrafluoroborate oxidant, thiaBF4. The crucial role of reagents and reaction conditions, like thiaBF4 over the magic blue oxidant and non-coordinating over coordinating solvents, are demonstrated for the isolation of high valent Pr(IV) complexes. The solid state structural and electrochemical properties were studied and further augmented with theoretical calculations. The Pr(IV) oxidation state was further confirmed by electron paramagnetic resonance (EPR) and SQUID magnetometry measurements. Complexes 5M-PrPh and 5[KDB18C6]-PrPh provide the first example of anionic Ln(IV) complexes demonstrating the possibility of accessing charged Pr(IV) complexes as a tool to manipulate the redox potential and therefore access to more stable complexes with the same ligand.
期刊介绍:
Chemical Science is a journal that encompasses various disciplines within the chemical sciences. Its scope includes publishing ground-breaking research with significant implications for its respective field, as well as appealing to a wider audience in related areas. To be considered for publication, articles must showcase innovative and original advances in their field of study and be presented in a manner that is understandable to scientists from diverse backgrounds. However, the journal generally does not publish highly specialized research.